/*
 * Copyright (C) 2018 CyberAgent, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.devyk.aveditor.video.filter.gpuimage

import android.content.Context
import android.opengl.GLES20

class GPUImageLaplacianFilter private constructor(context: Context,private var convolutionKernel: FloatArray?) :
    GPUImage3x3TextureSamplingFilter(context,LAPLACIAN_FRAGMENT_SHADER) {
    private var uniformConvolutionMatrix: Int = 0

    constructor(context: Context) : this(context,floatArrayOf(0.5f, 1.0f, 0.5f, 1.0f, -6.0f, 1.0f, 0.5f, 1.0f, 0.5f)) {}

    override fun onInit() {
        super.onInit()
        uniformConvolutionMatrix = GLES20.glGetUniformLocation(program, "convolutionMatrix")
    }

    override fun onInitialized() {
        super.onInitialized()
        setConvolutionKernel(convolutionKernel)
    }

    private fun setConvolutionKernel(convolutionKernel: FloatArray?) {
        this.convolutionKernel = convolutionKernel
        convolutionKernel?.let { setUniformMatrix3f(uniformConvolutionMatrix, it) }
    }

    companion object {
        val LAPLACIAN_FRAGMENT_SHADER = "" +
                "precision highp float;\n" +
                "\n" +
                "uniform sampler2D inputImageTexture;\n" +
                "\n" +
                "uniform mediump mat3 convolutionMatrix;\n" +
                "\n" +
                "varying vec2 textureCoordinate;\n" +
                "varying vec2 leftTextureCoordinate;\n" +
                "varying vec2 rightTextureCoordinate;\n" +
                "\n" +
                "varying vec2 topTextureCoordinate;\n" +
                "varying vec2 topLeftTextureCoordinate;\n" +
                "varying vec2 topRightTextureCoordinate;\n" +
                "\n" +
                "varying vec2 bottomTextureCoordinate;\n" +
                "varying vec2 bottomLeftTextureCoordinate;\n" +
                "varying vec2 bottomRightTextureCoordinate;\n" +
                "\n" +
                "void main()\n" +
                "{\n" +
                "mediump vec3 bottomColor = texture2D(inputImageTexture, bottomTextureCoordinate).rgb;\n" +
                "mediump vec3 bottomLeftColor = texture2D(inputImageTexture, bottomLeftTextureCoordinate).rgb;\n" +
                "mediump vec3 bottomRightColor = texture2D(inputImageTexture, bottomRightTextureCoordinate).rgb;\n" +
                "mediump vec4 centerColor = texture2D(inputImageTexture, textureCoordinate);\n" +
                "mediump vec3 leftColor = texture2D(inputImageTexture, leftTextureCoordinate).rgb;\n" +
                "mediump vec3 rightColor = texture2D(inputImageTexture, rightTextureCoordinate).rgb;\n" +
                "mediump vec3 topColor = texture2D(inputImageTexture, topTextureCoordinate).rgb;\n" +
                "mediump vec3 topRightColor = texture2D(inputImageTexture, topRightTextureCoordinate).rgb;\n" +
                "mediump vec3 topLeftColor = texture2D(inputImageTexture, topLeftTextureCoordinate).rgb;\n" +
                "\n" +
                "mediump vec3 resultColor = topLeftColor * convolutionMatrix[0][0] + topColor * convolutionMatrix[0][1] + topRightColor * convolutionMatrix[0][2];\n" +
                "resultColor += leftColor * convolutionMatrix[1][0] + centerColor.rgb * convolutionMatrix[1][1] + rightColor * convolutionMatrix[1][2];\n" +
                "resultColor += bottomLeftColor * convolutionMatrix[2][0] + bottomColor * convolutionMatrix[2][1] + bottomRightColor * convolutionMatrix[2][2];\n" +
                "\n" +
                "// Normalize the results to allow for negative gradients in the 0.0-1.0 colorspace\n" +
                "resultColor = resultColor + 0.5;\n" +
                "\n" +
                "gl_FragColor = vec4(resultColor, centerColor.a);\n" +
                "}\n"
    }
}
